Tool · repayment & affordability
What will your mortgage actually cost?
Enter a price, deposit, and term, the calculator shows the monthly payment, total interest, and whether it passes a lender's affordability test. It's pre-filled with the Bank of England's latest quoted 4.81% two-year fixed rate, and it runs entirely in your browser.
Data updated 2026-06-30
- 3.75%
- Bank of England base rate
- 4.81%
- quoted 2-yr fix, June 2026
- In-browser
- nothing sent to a server
Runs entirely in your browser, nothing you enter is sent to a server. Numbers update as you type.
Read the result this way
The monthly payment is what you'll actually pay; the total interest is what the loan costs you over its life; the affordability band is whether a lender's stress test, at your rate plus one percentage point, would pass it.
- Monthly
- your real budget line
- Total interest
- the true cost of borrowing
- Stress test
- rate + 1pp, ~35% of net income
How the calculator works
The monthly repayment uses the standard UK amortisation formula: M = P × (r × (1 + r)n) / ((1 + r)n − 1), where P is the loan, r the monthly interest rate, and n the term in months.
The affordability check applies the mainstream UK lender stress test: the borrower must afford the payment at the contract rate plus one percentage point (currently 4.75% on the base rate) with total monthly debt fitting within roughly 35% of net household income.
Next steps
The calculator is the maths; these turn it into a decision.
- Compare a 2-year against a 5-year fix at your LTV before you settle on a rate. Compare rates
- See how lenders actually assess affordability and the income multiples they use. Affordability guide
- Check the average price where you're buying so your inputs are realistic. House-price rankings
Results assume a capital-and-interest repayment mortgage; interest-only and buy-to-let work differently.
The default rate here is the Bank of England's latest quoted two-year fix. According to the HM Land Registry House Price Index, a series compiled from more than 1,000,000 registered property transactions a year, the average prices we use for affordability examples reflect completed sales; both datasets are published under the Open Government Licence. Our methodology explains the amortisation and stress-test formulas in full.
Related
Every figure on PlainMortgage is rendered directly from Bank of England and HM Land Registry data, no number is typed in by an editor. This calculator draws directly on Bank of England and HM Land Registry data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.